A. Field of the Invention
This invention relates generally to the field of dialysis and machines for performing dialysis therapy. More particularly, the invention relates to a bottle for containing dialysate chemicals, cleaning agents, or other substances that may be introduced in a dialysis machine treating a dialysis patient. The invention also relates to a chemical loading system and method for distinguishing different types of bottles from each other.
B. Related Art
Dialysis is a treatment for persons suffering from inadequate kidney function. A dialysis machine is an artificial kidney machine that treats the blood of a dialysis patient. Dialysis machines typically incorporate an extracorporeal blood circuit having a semipermeable dialyzer membrane. During dialysis therapy, blood from the patient is circulated through the extracorporeal circuit to the dialyzer membrane, where toxins and excess water are transported through the dialyzer membrane into a dialysate solution. The treated blood is then returned to the patient.
Dialysis machines also typically include a dialysate preparation system. This system prepares a dialysate solution by mixing concentrated chemicals (typically a mixture of sodium bicarbonate, an acid, solution, and additional minerals and salts) with reverse-osmosis filtered water.
Dialysate preparation systems come in two varieties, proportioning systems and batch systems. In proportioning systems, the concentrated dialysate chemicals are proportioned with water to provide a continuous supply of dialysis solution to the dialyzer. A representative proportioning system is described in Peterson et al., U.S. Pat. No. 5,487,827. In a batch system, an entire batch of dialysate solution is made in advance of the patient connecting to a dialysis machine. The batch of dialysate solution is typically made in the dialysis machine from a mixture of a batch quantity of dialysate solution chemicals and a large volume (e.g., 50 liters) of water. Representative patents describing batch systems are Twardowski, U.S. Pat. No. 5,336,165, and Kenley et al., U.S. Pat. No. 5,591,344. The entire contents of the Twardowski ""165 and Kenley et al. ""344 patents are incorporated by reference herein.
With a batch dialysate preparation system, the amount of dialysate solution chemicals needed to prepare a batch of dialysate solution is preferably measured out and packaged in a vessel, and the vessel shipped to the location where the machine is located. Typically, as taught in Kenley et al., the chemicals will include one vessel containing a liquid acid formulation and another vessel containing a powdered sodium bicarbonate formulation. This format for providing batch chemicals measured into batch chemical vessel bottles allows for careful control over the quantity of chemicals and the formulation, thereby promoting patient safety. The ready-to-use batch quantity bottles are also convenient for the user of the machine.
There are several technical problems in designing a suitable vessel for containing batch quantity dialysate chemical formulations. This is particularly the case where the bottles and dialysis machine may be used outside of a conventional dialysis clinic, such as in a home or nursing home environment. One challenge is to design the bottle and machine in a manner to minimize or eliminate the risk that the user of the machine may inadvertently install the wrong bottles on the machine (such as two liquid acid bottles instead of one acid and one bicarbonate). Another difficulty is designing the bottle so that the contents may be readily dispersed into the dialysate preparation system automatically, reasonably quickly, and without human intervention. This is particularly the case with a powdered bicarbonate chemical formulation, which has a tendency to clump if the vessel is exposed to heat such as may occur during shipping or storage, or if the bottle is exposed to hot water during a heat disinfection process.
Patents describing bottles specifically designed for containing batch quantities of dialysate solution chemicals include the above-referenced Kenley et al. ""344 patent, U.S. Design Pat. No. D 395,517; U.S. Pat. No. 5,788,099 and U.S. Design Pat. No. D 403,079, each of which is assigned to Aksys Ltd.
The present inventive bottle provides features that ensure that only the correct combination of bottles can be installed in the dialysis machine. Further, the bottle includes features that promote the removal of substantially all the contents of the bottle by a bottle opening mechanism in the dialysis machine. These and still other features of the bottle will be described in the following detailed description of the preferred embodiment of the invention.
In a first aspect, a bottle is provided for containing chemicals to be introduced into a dialysis machine. The bottle is adapted to be installed in a chemical loading system in the dialysis machine which opens the bottle and introduces the chemicals into a fluid path in the dialysis machine. The bottle comprises a cylindrical bottle shell having a sidewall defining a bottle axis, a shoulder portion, a corner portion at which the shoulder portion intersects the sidewall, a lower portion, and a mouth through which the chemicals may be withdrawn from the bottle. The bottle further comprises a detection feature, such as either at least one raised rim extending outwardly from the sidewall extending around the circumference of the sidewall in a manner perpendicular to the axis of the bottle, or a circumferential groove or indentation extending inwardly form the sidewall in a manner perpendicular to the bottle axis. The raised rim or, alternatively, groove, is positioned on the sidewall a predetermined distance from the corner portion of the bottle and the mouth of the bottle. When the bottle is installed on the chemical loading system, the rim or groove of the bottle is detected by a detection system in the chemical loading system. For example, optical or mechanical detectors may be positioned in the chemical loading system to detect the presence of the rim or groove of the bottle.
As will be explained below, the bottle may contain a powdered dialysate chemical formulation or a liquid acid formulation. A second type of bottle that does not have the raised rim or groove (i.e., the bottle sidewall is smooth) may be provided, which contains cleaning or disinfection chemicals. When the second type of bottle is installed on the chemical loading system, the absence of the rim or groove will be detected by the detection system. Thus, the system can differentiate between the bottles containing chemical cleaning agents and dialysate chemicals.
The detection of the rim of groove by the detection system will allow the control system to distinguish the contents of the bottles. For example, bottles having cleaning compositions may have a raised rim detection feature, whereas the bottles having powdered bicarbonate formulations may have a groove feature. This type of system is a simple and reliable way to automate the detection of the bottles in the chemical loading system, while distinguishing between different types of bottles that may be installed in the chemical loading system.
In another aspect of the invention, the liquid acid and bicarbonate formulations are stored in two different bottles. Both bottles have at least one raised rim (or, alternatively, indentation or groove) extending outwardly from the sidewall extending around the circumference of the sidewall in a manner perpendicular to the axis of the bottle, with the raised rim positioned on the sidewall a predetermined distance from the corner portion of the bottle and the mouth of the bottle. However, the shoulder and mouth of the two bottles are given a different configuration. The shoulder and mouth of the bicarbonate formulation bottle is given a configuration that promotes ready release of a powdered composition, such as a steeper shoulder configuration and a wider mouth.
In another aspect, the chemical loading system may contain two different chemical loading mechanisms. One mechanism is particularly designed and adapted to receive the bottle containing the bicarbonate formulation. The other mechanism is particularly designed and adapted to receive the bottle containing the liquid acid formulation. If the user inadvertently attempts to install the bottle containing the liquid acid formulation in the chemical loading mechanism for the bicarbonate formulation bottle, a mismatch or interference occurs. Similarly, if the user attempts to install the bottle containing the bicarbonate formulation on the liquid acid loading mechanism, a mismatch or interference occurs. This design provides a fool-proof way of insuring that the user can only install the bicarbonate and liquid acid formulation bottles on the correct chemical loading mechanisms.
In yet another aspect, the shoulder portion of the bottle comprises a frusto-conical wall having a cone angle that is optimized for dispersion of the contents of the bottle. For example, if the bottle contains a powdered bicarbonate formulation, the cone angle may between 60 and 70 degrees. If the bottle contains a liquid acid formulation, the cone angle may be lesser, such as between about 30 degrees and about 40 degrees. The frusto-conical wall is also given a predetermined height, and the mouth is given a diameter such as between 1 and 2 inches.
The neck portion of the bottle includes a set of bayonet screw threads adapted for mounting the bottle to the bottle opening mechanism. A second set of screw threads is also included in the neck. The second set of screw threads receives a cap providing protection for a heat-sealed membrane covering the top of the bottle. The bayonet screw threads will not engage the chemical loading system unless the cap has been first removed from the bottle.
In yet another aspect, the present invention provides a kit for preparation of a batch of dialysate solution in a dialysis machine. The kit includes a bicarbonate formulation contained in a first batch chemical vessel and a liquid acid formulation contained in a second batch chemical vessel. The first and second batch chemical vessels comprises a cylindrical sidewall defining a bottle axis, a shoulder portion, a corner portion at which the shoulder portion intersects the sidewall, a lower portion, and a mouth through which the chemicals may be withdrawn from the bottle. The shoulder portion of the first batch chemical vessel comprises a frusto-conical wall having a first cone angle and a first height, and wherein the mouth has first diameter. The shoulder portion of the second batch chemical vessel also comprises a frusto-conical wall, but the cone angle is different from cone angle of the first bottle. The height of the shoulder of the second bottle is also different from the height of the shoulder of the first bottle. Further, the mouth of the second vessel has a second diameter different from the diameter of the first vessel. These differences in cone angle, shoulder height, and mouth diameter cooperate with first and second bottle mounting structures adapted to receive the first and second bottles, respectively, in the dialysis machine to thereby prevent the first and second bottles from being inadvertently installed on the second and first bottle mounting structures, respectively.
In another aspect of the invention, a chemical loading system is provided which comprises optical or mechanical detectors for detecting the presence of a physical configuration on the exterior of the bottle (e.g., raised rim or goove) to discriminate between two different types of bottles. The detection system can be either an optical detection system or a mechanical detection system.
Further aspects and features of the present invention will be more apparent from the following detailed description and the appended drawing figures.